This disclosure relates to polyimide compositions, and in particular hydrostable blends of polyetherimide/polycarbonate and polyetherimide/polycarbonate-ester compositions, as well as their method of manufacture and articles formed from the polyimide compositions.
Polyimides (PI), and in particular polyetherimides (PEI), are amorphous, transparent high performance polymers having a glass transition temperature (Tg) of greater than 180° C. These polymers further have high strength, heat resistance, and modulus, and broad chemical resistance. Polyetherimides are widely used in applications as diverse as automotive, telecommunication, aerospace, electrical/electronics, transportation, and healthcare. Filled and unfilled PEI compositions further comprising a polycarbonate (PC), polycarbonate-ester (PCE), and/or polyalkylene terephthalate (PET) are particularly useful as molded parts for metal replacement, for example in automotive and electrical/electronic applications. PEI-PC, PEI-PCE, and PEI/PET blends have good mechanical and thermal properties, including excellent dimensional stability at high temperatures.
There has long been a need in the art for PEI/PC, PEI/PCE, or PEI/PET compositions, in particular PEI-PC and PEI-PCE compositions that are more hydrostable. Such compositions would be useful for the manufacture of articles used in the food service and the medical industries, which are required to undergo sterilization conditions that are often stringent. Although PCE has the impact strength needed for these applications, there remains a continuing need for compositions that can withstand the autoclave sterilization procedure. Conversely, PEI can withstand the autoclave sterilization procedure but is too brittle to meet the toughness requirement. Thus, there is a long felt need for the development of ductile compositions that are able to withstand repeated sterilization conditions, particularly autoclave conditions, without distorting, cracking, or blistering. It would further be advantageous if improved hydrostability could be achieved without significantly adversely affecting the good mechanical and thermal properties of the compositions, such as ductility.